I consider this button to be not much more than a demo since it fails most of the time, then in some cases installs a failing driver.
I strongly suggest ignoring this button.
It's not a joke button, but Microsoft can't get all the hardware makers onboard.
Win XP has a Hardware Update Wizard which can connect to Windows Update, and search for updated drivers. I have used the Wizard several times to try to update a printer driver, but it always said "the wizard could not find a better match". Problem is - there WAS a better match, and when I downloaded (from the manufacturer) and installed the updated driver, it cured a long-term glitch in my system. Is this Hardware Update Wizard a complete joke that everyone should avoid? With my recent experience, I certainly won't trust it to inform me as to whether or not there is a better device driver available.